Blade fastening



' March 1, 1927.

A. T. KASLEY BLADE FASTENING Filed Jan. 7, 1922 Patented Mar. 1, 1927.

"UNIT E D ST AiT ALEXANDER T. KASLEYJOF n'ssnveron,

-VANIA.

PATIENT our-regs.

PENNSYLVANIA. nssrenon T wnsrrne BLADE FASTENING.

-App1ication filed January v7, 1922, :Seria1 No.=527;S74.

Y -My invention relatesitoelastic-fiuid turbines, and more particularly to \those employin g relatively.wideblades,and it has for its object to provide rotor and blade; connections'which shallzbe easy and cheap toconstruct, reliable and durable .in operation, and which shall be maintained tight at all times. 7

Apparatus embodying features of my .invention is :illustrated .on the accompanyi drawings, forming apart of this application, in which Fig. 1 isa longitudinal sectional view of a portion 'of a turbineshowing --1nyinvention applied thereto; Fig. 2 is .a sectional view taken :along the line II II-of=.Fig. 1; Fig. 3 .isardetailsectional view=taken-alongthe line lllflll of Fig. 1 :FigsJt and. 5. show modified; forms of the key means shown in connection with Figs. 1and2;Fig. 6 isapersp'cctivevieiv of a portion of atubularkey; Fig.7 is .adetail vievvishowing how the hollow form ofkcy means may be boredout; andgFigs. 8 and 9 show further modified formsof key devices.

In= my 'application,Serial N- 486,517, filed July 2, .1921, assi-gned tothe iWestinghouse Electric & Manufacturing Company, there is disclosed a novel "orm of relatively wideturbine blading which is adapted to receive elastic fluid at one side and to .discharge it aatrtheltips or peripherally. NVith blading of this type, it is necessary, on account of the extreme width, to secure the blades .inxslots extending longitudinally of the rotor, instead of circumferentially thereofi as isusually the case with blades of normal Width. Accordingly, .it is the object of my-present invention to provide a rotor with longitudinally extending slots, having inclined sides andto iprov-ide blades with complementally iforme'droot portions adapted to'fit the slots. Preferably .the slotsand theroot portions are .of the donbleedovetail type and recesses for tightening keys may be provided in'theIbottoms ,of-jthe slots or in the bottoms of the slots and at the bottoms of the blades.

Referring now to the drawings for a more detailed description of my invention, I show portions of a cylinder 11 and of a rotor 12 of an elastic-fluid turbine carrying suitable energy-abstracting elements, including a last low-pressure stage 13, comprising a stationary row of guide blades 14 and a row of relatively wide blades 15, adapted torecelve steam oreiastic'fiuid at thesides adiacent to theguide blades 1d and to: discharge C S me peripherally or tth t The relatively wide blades are provided with inner substantially radialor port ons 16, and with outer curved. or spoonoutline portions 1?. (SeeFig. :Theinner portions 16 arepreferably}provided with a plurality of guide ribr19cfor the purpose of deflecting steam fronr an axial toward-aradial direction and. of bracing the blading structure. A

The-blades 16 are provided with root portions 20 0f the double dovetail type, adapter to fit correspondingly shaped slots 21 formed in the rotor 12. Thedovetail slots 21 are provided with countersunk grooves orslots 22to receive suitable .keys23, which are inserted for the purpose of forcing the inclined surfaces ofthe dovetail vrootportions 20 firmly in contact with the inclined surfaces of the dovetail slots 21.

In Figs. 1, 2, a, 5, and.6,-I show keys 23 Which are tubular in form, which may be readily inserted, and which, after insertion, may be expanded in any suitablemanner to securea tight fit between the, groove and the blade root and force thejn'clined faces of the dovetailportions ofthe root 2O tightly into contact with theEinclined faces ofthe dovetail grooves21. The tubnlarkeys-f-or each blade may be made in sectioinas Shown in Fig. .1, or such'keys may bemade insingle pieces. The tubular form of :key

is advantageous for the reason that it may be readilybored out when it is desired to remove a blade, as will be evident frozna consideration of Fig. 7, which shows a suitable boring tool .24 operatively related with respect tothe tubular key 2 for the purpose of boring the latter out.

InFig. 2,' the bottomof the root portion is provided with agroove 25 whichfits the key. In Fig. 4, the root portion 20 of the blade is provided with a projection 26 extending into countersunk groove 22 and having a groove 25 Which fits the key 23. In Fig. 5, the bottom faces of the root portion '20 of the blade are not modified, but are provided With bottom plane faces which contact With the keys 23. The last-named construction is advantageous from the standpoint of cheapness, as the root portion of the blade may be more easily formed.

In Figs. 8 and 9, I show further modified forms of keys for the dovetail root portions in which solid keys are used. In Fig. 8, the key 27 is formed of a cylindrical bar, and in Fig. 9, the key takes the form of a rectangular bar 28.

From the foregoing, it will be apparent that I have devised a type of fastening for wide blades which possesses adequate strength, which is cheap to make, and which provides for the maintenance of the blade connections tight at all times.

While I have shown my invention in a plurality of forms, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various other changes and modifications, without departing from the spirit thereof and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

IVhat I claim is:

1. In a. turbine, the combination of a rotor having dovetail slots, a plurality of blades having dovetail root portions fitting in the slots, and an expansible key arranged between the bottoms of the slots and the bottom portions of the blades for holding the latter tightly in the slots.

2. In a turbine, the combination of a retor having a plurality of slots with overhanging sides, a plurality of blades having root portions formed complementally with respect to said slots, and an expansible key means arranged between the bottoms of the slots and bottom portions of the root portions to hold the latter tightly in place with respect to said slots.

3. In a turbine, the combination of a 1'0 tor having longitudinally extending slots with inclined and overhanging sides, a plurality of blades having roots provided with complemental portions adapted to fit within said slots, and expansible key means arranged between the root portions and the bottoms of the slots in order to hold said blades tightly in place with respect to the rotor.

4. In a turbine, the combination of a rotor having a plurality of slots with inclined overhanging sides, a plurality of blades having root portions formed complen'ientally to said slots, and expansible tubular key means arranged between the root portions and the bottoms of the slots in order to maintain the blades tightly in place with respect to the rotor.

5. In a turbine, the combination of a rotor having longitudinally extending dovetail slots with key grooves in the bottoms thereof, a plurality of blades having dovetail root portions adapted to fit said dovetail slots, and tubular expansible key means arranged in the recesses and contacting with the bottoms of said root portions to maintain the blades tightly in place With respect to the rotor.

6. In a turbine, the combination of a rotor having a plurality of longitudinally eX- tending dovetail slots with arcuate recesses in the bottoms thereof, a plurality of blades having dovetail root portions adapted to fit said slots and arcuate recesses in the bottoms thereof, and a plurality of tubular keys adapted to fit in the arcuate recesses of the slots and the root portions and adapted to be expanded in order to force the dove tail portions of the blades tightly into contact with the dovetail portions of the slots.

7. In an elastic-fluid turbine, the combination of a rotor having a plurality of dovetail slots, a plurality of blades having dovetail root portions adapted to fit in the slots, and sectional expansible key means arranged between the bottoms of the slots and the root portions for holding the blades firmly in place with respect to the rotor.

8. In an elastic-fluid turbine, the combination of a rotor having longitudinally extending dovetail slots, a plurality of blades having dovetail root portions fitting in the slots, sectional tubular, expansible key means arranged in the slots between the bot toms thereof and said root portions, and adapted to be expanded in order to hold the blades firmly in place with respect to the rotor.

9. In a turbine, the combination of a. rotor having a. plurality of blade slots, a pinrality of blades having root portions fitting in the slots, and expansible key means for holding the blades in the slots, the key means being provided with a central opening in order that said key means may be readily expanded or may be readily bored out with a drill when it is desired to remove a blade.

In testimony whereof, I have hereunto subscribed my name this 4th day of January, 1922. ALEXANDER T. KASLEY. 

